1. Field of the Invention
The invention relates to a cartridge-type filter unit used in a well fluid cleaning system.
2. Description of the Prior Art
In gravel packing and other operations involved during the production or workover of a subterranean well, it is desirable, for a number of reasons, to circulate through the well from the surface a fluid, which, for example, may be a carrier fluid for particulate matter, such as gravel. Such fluid may incorporate a number of additives, and may be provided in the form of a viscous jell, or the like. Regardless of the composition or use of such fluid, it is necessary that contaminants carried with the fluid during its circulation through the well be removed at the surface of the well prior to recirculation of the fluid.
Referring to FIG. 1, a conventional well cleaning system comprises a filtration unit 100 having one or more filter members, generally in series, communicating to a source fluid line 13 extending from a centrifugal pump 10, or other pump, driven by a power source 11, such as a diesel or electric engine, or the like. A dry hopper 12 may be provided along the flow line for incremental addition of fluid additives. Clean fluid is transferred from the filtration unit 100 by means of the clean fluid line 15 which extends to a clean fluid storage area 14B in a fluid storage tank 14. A source fluid storage area 14A contains dirty fluid removed from the well which is thereafter transmitted to the centrifugal pump 10 through a source fluid line 13A.
FIGS. 2A and 2B illustrate prior art and conventional cartridge assemblies. Referring specifically to FIG. 2A, a prior art cartridge apparatus A is exteriorly defined by an elongated cylindrical housing B containing therein a series of spaced filter cartridges C secured to a plate E in the housing B by means of a bolt D. Inlet line IL and outlet line OL communicate through the housing B for the transmission of the fluid.
Now referring to FIG. 2B, illustrating in longitudinal cross-section a typical filter cartridge C, the bolt D is inserted through a bore G in the washer F on the top of the filter cartridge C and is secured by threads H to an elongate tube J interiorly housed within the filter cartridge C. The tube J has a number of circumferentially and longitudinally spaced flow passages I communicating with the annular area defined between the interior of a surrounding filter cartridge C and the exterior of the tube J for transmission of cleaned fluid passing through the filter cartridge C, into the flow passage I, thence inwardly within the bore of tube J and through the open end M communicating to the lowermost portion of the cylindrical housing B below the plate E, for subsequent recirculation into the well bore. The tube J is affixed to a cartridge receiving bore (not shown) in the plate E by means of threads L. An orienting shoulder K circumferentially extends around the lowermost end of the tube J and above the threads L and is defined above an outwardly extending lip N which receives the lowermost end of the filter cartridge C thereon. Thus, the filter cartridge C may be located on the lip N and exterior of, or upon, the orienting shoulder K.
When the filter cartridge assembly as depicted in FIGS. 2A and 2B is utilized, it is necessary to first disengage the bolt D from the tube J and thereafter lift the filter cartridge C upwardly over the uppermost end of the tube J. This must be repeated for each filter cartridge assembly contained within the apparatus A. The inconvenience factor of this approach will be readily appreciated when one considers that this series of steps must be repeated for each filter cylinder A utilized in series, such as the series illustrated for the filtration unit 100 in FIG. 1. Such a procedure is extremely costly and time consuming.
Additionally, the removed cartridges are difficult to clean for reuse and are generally scrapped and replaced.
The present invention provides a method and apparatus which completely overcomes the disadvantages of the use of typical prior art apparatuses, as shown in FIGS. 2A and 2B.